Halogen-free flameproof polycarbonate blends are known. U.S. Pat. No. 5,204,394 describes for example polymer mixtures of polycarbonate, a styrene-containing copolymer and/or a styrene-containing graft polymer that have been rendered flameproof with oligomeric phosphoric acid esters. Examples of such polymer mixtures are PC/ABS blends and PC/HIPS blends.
For some applications it is desirable to provide compositions with comparable or improved properties that do not contain polymer components in whose structure styrene, butadiene and/or acrylonitrile are involved as monomer components. Such polymers and therefore also the compositions containing these polymers always contain, due to their production, traces of residual monomers including styrene, butadiene and acrylonitrile, which are regarded as critical for the use of the products produced therefrom in some applications.
In JP-A 08 259 791 and JP-A 07 316 409 compositions are described that contain, in addition to polycarbonate, also a methyl methacrylate (MMA)-grafted silicone/acrylate composite rubber, a monomeric or oligomeric phosphoric acid ester, and polytetrafluoroethylene (PTFE). These compositions are flameproof and have a high notched impact strength. The flowability of such compositions is however as a rule insufficient, especially if in order to achieve a good resistance to chemicals a polycarbonate with a sufficiently high molecular weight is used, and to achieve a satisfactory thermal stability a sufficiently small phosphoric acid ester fraction is employed. Similar comments apply to the compositions that are described in U.S. Pat. No. 6,423,766 B1 and U.S. Pat. No. 6,369,141 B1.
EP-A 0 463 368 describes compositions of polycarbonate, PMMA, ABS and a monomeric phosphoric acid ester that are flameproof and are characterized by an improved flow line strength. These compositions do not however satisfy the aforementioned desire for materials that are free of styrene, butadiene and acrylonitrile.
The object of the present invention was to provide flameproof polycarbonate compositions that do not contain any polymers built up from any of butadiene, styrene and acrylonitrile and are thus free of butadiene, acrylonitrile and styrene residual monomers, and that are characterized by a good property combination of improved flow line strength, resistance to chemicals, elongation at break and thermal stability with, compared to equivalent PC+ABS compositions, an unchanged good processability in injection molding processes, i.e. that are characterized by melt flowability and flame resistance.